We're going to have to face the fact that folding phones are the thing for 2019. And phone design tends to go like this, with 2017 being the year of the notch and 2018 being the year nothing happened.

Chinese company Xiaomi is the latest to hint at a folding phone. In a video demo a device is shown that folds into three sections.

The middle is the main part of the device, and it's what will make up the phone when the two sides are folded in.

And those sides are designed to give you a little more screen space when you need it, but that will fold away when you need to tuck the phone in your pocket.

It's hard not to be impressed by folding phones that look as good as this one. They take us ever closer to the tablets we see in TV shows like Westworld, which fold to pocket size and open up to iPad Pro dimensions.

Xiaomi seems to have done a pretty good job designing the folding mechanism on this prototype, it folds neatly and seems able to tell that fingers touching the folded sides should be ignored by the UI.

This sort of detection is important because a phone would be unusable if the back of it was a touch screen while folded.

But like all of these devices it's not clear what the actual problem they're trying to solve. Sure, a larger screen would always be nice but will people pay a presumably massive premium to get these devices.

Plus there are the concerns about damaging these devices. Putting cases on them is going to be impossible, so the first drop could finish them off.

As with all cutting edge innovation it's likely that most people will just want to skip the first two generations of folding phones. It's worth picking them up again when they tech has evolved and when the prices come down.

For now it makes a nice trade show reveal, but little more practically speaking.